On receipt of a request for a communication session over a communications network, such as an Internet Protocol communications network, a path for the session is established. In a preferred example the communications network is an MPLS network and the method uses a modified version of the SIP messaging protocol. Bandwidth along a chosen path is reserved and a messaging protocol such as CR-LDP used to establish this reserved path for the communication session. This creates a delay in the time taken to establish a communication session because the process of choosing a path and reserving bandwidth must be completed before the CR-LDP protocol is used. This delay is reduced by using modified SIP Protocol to perform the CR-LDP function too.